<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>计数器</title>
    <link rel="stylesheet" href="">
</head>

<body>
    <div id="app">
        <div class="input-num">
            <button @click="sub">-</button>
            <span>{{ num }}</span>
            <button @click="add">+</button>
        </div>
        <img src="http://www.itheima.com/images/logo.png" alt="">
    </div>
    <!-- 开发环境版本，包含了有帮助的命令行警告 -->
    <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
</body>
<script>
    var app = new Vue({
        el: "#app",
        data: {
            num: 1
        },
        methods: {
            add: function () {
                console.log('add')
                if (this.num < 10) {
                    this.num++
                } else {
                    alert("别点啦，最大啦!")
                }
            },
            sub: function () {
                console.log('sub')
                if (this.num > 0) {
                    this.num--
                } else {
                    alert("别点啦，最小啦!")
                }
            }
        }
    })
</script>

</html>